Ru- and Cl-Codoped Li3 V2 (PO4 )3 with Enhanced Performance for Lithium-Ion Batteries in a Wide Temperature Range.

Abstract

Li3 V2 (PO4 )3 (LVP) is a promising cathode material for lithium-ion batteries, especially when used in a wide temperature range, due to its high intrinsic ionic mobility and theoretical capacity. Herein, Ru- and Cl-codoped Li3 V2 (PO4 )3 (LVP-Rux -Cl3 x ) coated with/without a nitrogen-doped carbon (NC) layer are synthesized. Among them, the optimized sample (LVP-Ru0.05 -Cl0.15 @NC) delivers remarkable performances at both room temperature and extreme temperatures (-40, 25, and 60°C), indicating temperature adaptability. It achieves intriguing capacities (49 mAh g-1 at -40°C, 128 mAh g-1 at 25°C, and 123 mAh g-1 at 60°C, all at 0.5 C), long cycle life (94% capacity retention after 2000 cycles at 25°C and 5 C), and high-rate capabilities (up to 20 C). The structural evolution features and capacity loss mechanisms of LVP-Ru0.05 -Cl0.15 @NC are further investigated using in situ X-ray diffraction (XRD) at different temperatures (-10, 25, and 60°C) during redox reactions. Theoretical calculations elucidate that Ru- and Cl-codoping can greatly improve the intrinsic diffusion coefficient of LVP by reducing its bandgap energy and lowering the energy barrier of lithium-ion diffusion. In "all-weather" conditions, the dual-element co-doping strategy is critical for increasing electrochemical performance.